A cellular telecommunications system is a communication system that is based on use of radio access entities and/or wireless service areas. The access entities are typically referred to as cells. Examples of cellular telecommunications systems include standards such as the GSM (Global System for Mobile communications) or various GSM based systems (such as GPRS: General Packet Radio Service), AMPS (American Mobile Phone System), DAMPS (Digital AMPS), WCDMA (Wideband Code Division Multiple Access), TDMA/CDMA (Time Division Multiple Access/Code Division Multiple Access) in UMTS (Universal Mobile Telecommunications System), IMT 2000, i-Phone and so on.
In a cellular system, a base transceiver station (BTS) provides a wireless communication facility that serves mobile stations (MS) or similar wireless user equipment (UE) via an air or radio interface within the coverage area of the cell.
A feature of the cellular system is that it provides mobility for the mobile stations. In other words, the mobile stations are enabled to move from a location area to another location area. The mobile stations may even roam from a network to another network that is compatible with the standard the given mobile station is adapted to. A feature of the mobility function is that it records location area information concerning the location of a particular mobile station in a given moment of time. A cellular communications system typically comprises a location register or several location registers for the location management purposes. The location management function typically operates such that whenever a mobile station enters a new location or routing area, the location area information associated with the mobile station is updated at an associated location register or several registers.
For example, in a circuit switched GSM (Global System for Mobile) network a controller function is provided by means of a mobile switching centre (MSC). The location information of a mobile station is maintained centrally by a home location register (HLR), wherein the mobile station is permanently registered as a subscriber profile at the home location register. At the same time the mobile station is registered locally by a visitor location register (VLR). A VLR is typically implemented in connection with the MSC, but the system handles the MSC and the VLR as separate logical entities. The mobile station will be registered only temporarily to the visitor location register. Each of the mobile switching centres (MSC) is typically provided with a visitor location register. The VLR at which the mobile station is temporarily registered at a given moment is the VLR of the MSC that is currently serving the mobile station. The HLR may be a stand alone element in the network or the HLR may be integrated with another network element, such as located within one of the switching centres provided in the network. Even though it is not necessary, the arrangement is typically such that the HLR knows the VLR at which the MS is currently registered and the VLR knows then the actual location area (LA) within which the MS is currently located.
Information of the location area is needed for various purposes. For example, when somebody tries to establish a call terminating at a mobile station or send a short text message to the mobile station, the communication system has to be aware of the location area so that it may route the call related signalling and the call into a correct location area and page the mobile station in that area.
Accordingly, although subscriber profiles are permanently registered at the HLR, a subscriber only needs to be registered on the HLR if the subscriber is active, i.e. at times when a subscriber may make or receive a call. However, at present a large amount of storage space on HLRs is taken up by profiles for subscribers who are inactive, i.e. those who are not able to place and/or receive calls. This means that the storage space of the HLR that stores profiles for subscribers who are inactive is effectively wasted. Since the cost of storage space is expensive, this is highly undesirable.
Subscriber information in a mobile communication system may also be stored in a number of other elements such as Voice Mail Systems, Short Message Service Centers, IN-servers, Multimedia Messaging Center. The subscriber information in these elements is provisioned typically at the same time as in the HLR, so the same waste of storage space issues also concern these elements. For provisioning purposes typically a dedicated provisioning solution is used, hereafter provisioning gateway.
For example, subscriber profiles are created on the HLR for SIM (subscriber identity module) cards sold in the so called ‘prepaid’ mobiles. Prepaid mobiles are those which can be bought of the shelf without the need for a contract. In order to make calls from the mobile the user must pay the network operator in advance of making any calls. Before the prepaid mobiles are sold and registered by the user, the storage space on the HLR allocated to the unsold phone generates no revenue and is therefore wasted.
A further example of when the storage space of the HLR is taken up by a subscriber and generates no revenue is when a prepaid subscriber keeps their credit balance at zero. One solution to this problem is to delete the subscriber profile from the HLR after a predetermined time, typically a couple of months. However this solution is unsatisfactory since when the subscriber wishes to resume use of their prepaid mobile, they are required to purchase a new SIM card.
A still further example is when a post paid subscriber becomes temporarily inactive. The inactive state may last a substantially long time (e.g. the subscriber is abroad or using another subscription.) Despite the inactive state, the network operator may have legal obligations to maintain the subscriber record at the HLR; or the network operator may not wish to force the subscriber to buy a new SIM card if the subscriber wishes to revert to using the subscription.